"We have some doubts that we need to check and which will be debated in the coming days in the Security Council," Reynders, whose country was Congo's former colonial power, told Belgian public broadcaster RTBF.

Democratic Republic of Congo's electoral commission on Thursday declared opposition leader Tshisekedi the winner of last month's chaotic presidential election, but the runner-up dismissed the outcome as an "electoral coup". (Reporting by Alastair Macdonald and Robin Emmott; Editing by Janet Lawrence; @macdonaldrtr)